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Abstract: PO0002

Expression of SARS-CoV-2 Viral Protein ORF3A in Renal Tubular Epithelial Cells Induces Injury

Session Information

Category: Coronavirus (COVID-19)

  • 000 Coronavirus (COVID-19)

Authors

  • Zhou, Weibin, Icahn School of Medicine at Mount Sinai Department of Medicine, New York, New York, United States
  • Cai, Hong, Icahn School of Medicine at Mount Sinai Department of Medicine, New York, New York, United States
  • Chen, Ya, Icahn School of Medicine at Mount Sinai Department of Medicine, New York, New York, United States
  • Lee, Kyung, Icahn School of Medicine at Mount Sinai Department of Medicine, New York, New York, United States
  • He, John Cijiang, Icahn School of Medicine at Mount Sinai Department of Medicine, New York, New York, United States
Background

The coronavirus SARS-CoV-2 is the culprit of the COVID-19 pandemic. Acute kidney injury occurs frequently in COVID-19 patients and several lines of evidence suggest local infection of kidney cells by the virus. However, this remains controversial and it is unclear how the viral proteins of SARS-CoV-2 directly impact the health of renal tubular cells infected by the virus.

Methods

The viral protein ORF3A of SARS-CoV-2 was overexpressed in HK-2 renal tubular cell line and the pronephric tubule epithelia of transgenic zebrafish. The NF-kB and STAT3 signaling pathways and target gene expression were analyzed using quantitative RT-PCR and Western blots. The expression of the renal injury marker KIM-1 was also assessed by Western blots, quantitative RT-PCR and in situ hybridization. Protein interactions were studied by co-immunoprecipitation and Western blots.

Results

ORF3A augments both NF-kB and STAT3 signaling by enhancing the phosphorylation of the transcription factors and results in the expression of downstream target genes and subsequently increases the expression of kidney injury molecule 1 (KIM-1) in HK-2 cells. Mechanistically, ORF3A elevates the expression of Tripartite Motif-Containing Protein 59 (TRIM59), a ubiquitin E3 ligase, which forms a protein complex with ORF3A and STAT3. This in turn excludes the phosphatase TCPIP from binding to STAT3 and inhibits the dephosphorylation of STAT3. The transgenic zebrafish expressing ORF3A in renal tubular epithelia develop severe edema starting 48 hours post fertilization and in situ hybridization shows elevated kim-1 expression in the pronephric tubules, indicating that ORF3A induces renal injury in zebrafish in vivo.

Conclusion

These results demonstrate that overexpression of ORF3A is sufficient to injure renal tubular epithelial cells and uncover a previously unrecognized molecular mechanism underlying the deregulation of STAT3 activity by ORF3A that leads to renal tubular cell injury. Altogether, the results of this study support the notion that direct infection of renal epithelial cells by SARS-CoV-2 may contribute to the renal complications in COVID-19 patients.

Funding

  • NIDDK Support